Heat exchanger



May 6, 1952 s. c. coLLlNs HEAT EXCHANGER Filed Jan. 20, 1948 2@ CZ/ @94- @22 e 35 4 Sheets-Sheet l @y MMI/@mw May 6, 1952 s. c. coLLlNs 2,596,008

HEAT EXCHANGER Filed Jan. 2o, 194e 4 sheets-sheet 2 @y MAM-m. azy.

S. C. COLLINS HEAT EXCHANGER May 6, 1952 4 SheetswSheet 3 Filed Jan. 20, 1948 llllllHllllllllH i w W n S. C. COLLINS May 6, 1952 HEAT EXCHANGER 4 Sheets-Sheet 4 `Filed Jan. 20, 1948 @@@QQQQW Patented May 6, 1952 HEAT EXCHANGER Samuel Cornette Collins, Watertown, Mass., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application January 20, 1948, Serial No. 3,217

2 Claims. 1

My invention relates to heat exchangers and particularly to heat exchangers which are well adapted, though by no means confined, to use in plants for the separation of gases.

The chief criterion of a superior heat exchanger is its efficiency, which is based upon the quantity of heat transferred per degree in difference of temperature between the counter-streams. Such efficiency can be promoted, I have found, by providing constructions in which the material streams separated by and caused to flow at opposite sides of relatively thin Walls through which heat transfer is to be effected are made laterally of relatively great dimension compared with what might be called their depth, and by placing in the streams of materials many turbulence creating obstructions-obstructions which do not unduly interfere with the movements of the desired quantities of fluid but which nonetheless result in a continuous internal remixing of the masses of flowing fluids, so that stratified temperature changes are avoided, and so that layers which have been warmed (or cooled) in such a manner as substantially to reduce the temperature differential between them and the walls which they contact are mixed with the portions of the fluids which differ more substantially in temperature from vsuch walls. Moreover, I have found that by utilizing plates having projections or protuberances extending in opposite directions from their principal planes, and placing plane plates in alternation with the plates having the projections or protuberances formed thereon, it is possible to produce a construction which accomplishes the advantages mentioned above and which also possesses suicient strength to permit substantial pressure differentials at the opposite sides of any of the walls thereof. For convenience in reference to them, but not by way of limitation,

I will refer to the plates having projections from them as being dimpled or beaded plates, meaning thereby that the metal is deformed so as to pro vide hollow domed or concavo-convex projections therefrom. Except as may be necessitated by the prior art or indicated in the appended claims, however, the feature of the hollowness of the projections is not to be considered an essential characteristic of the beaded plates. However, when I use the term dimpled, it is to be understood as denoting the use of recessed projections. I i

have further found that by utilizing plates as set forth, with ypartition elements as in the form of bent wires arranged between adjacent plates, and by the use of appropriate headers with, in some cases, separator rings as well as other separator elements, a very readily constructed as well as efficient heat exchanger can be provided. I have further found that the employment of telescoping or nesting pan sections with protuberances projecting outwardly from the pan sections a distance suiicient to engage other pan sections provides a very simple and strong heat exchanger, and that instead of protuberances formed from the metal of and projecting from the pan sections or plate sections other turbulence and stiffness providing structures may be employed as hereinafter set forth.

It is an object of my invention to provide an improved heat exchanger, meeting the standards of efficiency above set forth and readily constructed. It is another object of my invention to provide an improved heat exchanger. It is a further object of my invention to provide an improved heat exchanger employing improved -passage formingI means for the confining and guiding of the fluid treated therein. It is a further object of my invention to provide an improved heat exchanger having improvedk means operative both to improve its efficiency of performance and to adapt it for use with uids which may be at opposite sides, under substantially different pressures,

lof separating heat transfer walls. It is another object of my invention to provide an improved heat exchanger having improved header elements and header arrangements. It is still another object of my invention to provide an improved heat exchanger having improved passage forming elements. It is yet a further object of my invention to provide an improved heat exchanger having improved turbulence creating elements arranged in the flow passages thereof. It is still another object of my invention to provide an' improved heat exchanger having improved heat transfer effecting arrangements. It is another object to provide an improved heat exchanger element. Other objects and advantages of my invention Vwill hereinafter appear.

In the accompanying drawings, in which a number of illustrative embodiments and several modications which my invention may assumein practice are shown,

Fig. 1 is an elevational view of a vertically disposed heat exchanger, parts being broken away to show interior construction, and a substantial section between the ends of the device also being broken out to reduce the space required by the view.

Fig. 2 is another elevational view of the structure which is shown in Fig. 1, turned through Fig. is a fragmentary horizontal sectional view on the plane of the line 5-5 of Fig. 3.

Fig. 6 is a face view of a gaskt used between a header and the main bank or package of heat exchange elements.

Fig. 7 is a view generally similar to Fig. l, but

Without parts broken away, the arrangement being one for the effecting of heat interchange between three, rather than two, fluids.

Fig. 8 isa fragmentary View of a portion of the structure shown in Fig. 7, turned through 90', partially in elevation and partially broken away, to show details of construction.

Fig. 9 is a fragmentary sectional view on the vertical plane of the section lineeof Fig. 7.

Fig. 10 is a similar view on the plane of the sectionline lll-lll of Fig. 7.

Fig. 11 is a vertical sectional view on the plane of the section line l I--I I of Fig. 8.

Fig. 12 is a corresponding vertical section on theplane of the line |2-l 2 of Fig. 8.

Fig. 13 is a vertical section on the plane of the line l3|3 of Fig. 8. Y

Fig. 14 is a horizontal transverse section on the plane of the line lli-I4 of Fig. 7.

Fig. 15is a horizontal transverse section on the plane of the line l 5--l5 of Fig. 7.

Fig..16 is a face View of a gasket.

Fig. 17 is an elevational View with parts broken away showing a modifiedform of two pass or two course heat exchanger.

Fig. lisanother elevational view of the structure shown in Fig. 17, turned through 90 and with parts broken away to show internal construction.

' Fig. 19is a vertical longitudinal sectional view Vtaken on the plane of the'line |9-l9 of Fig. 17,

central Vportions of the view being omitted to .reduce the size requirements of the drawing, the

view being on an enlarged scale.

Fig. 20 is a view similar to Fig. 19, taken on the plane of the section linev 2li-20 of Fig. 17. Fig. 21 is a vertical sectional view on the plane of the line 2 l-2l of Fig. 19.

Fig. 22 is a fragmentary horizontal transverse sectional view on the plane of the line 22-22 of Fig. 21. l

Fig. 23 is a view'on a somewhat larger scale showing a pan form plate section adapted for use in an exchanger of the type shown in Figs. 17 and 18.

Fig. 24 is another view of the 'pan or uplate section of Fig. 23, turned through 90, with Y parts broken away to show ndetails v'of construction.

' Fig. 25 is an enlarged `fragmentary vertical sectional view on Vthe plane fof the section line 25-25 of Fig. 23.

Fig. 26 is an enlarged fragmentary vertical sectional view on the plane of the line 23-26vof Fig. 23. w

Fig. 27 is an elevational view, shortened in Fig. 29-is a vertical sectional View approxi- Y mately on the plane of the line 2929 of Fig. 23.

Fig. 30 is a considerably enlarged fragmentary sectional view showing details of construction of the nested pans of Fig. 29.

Fig. 31 is a view similar to Fig. 23 showing another arrangement of means for effecting turbulence and preventingcollapse of the heat exchanger structure.

Fig.V 32 is anenlarged fragmentary vertical sectional view on the 'plane of the line 32-32 of Fig. 3l. f

Fig.33 is a fragmentary view, with parts partially shown in full, on the plane of the section line 33-33 of Fig. 32.

Fig. 34 is an enlarged fragmentary viewshow Fig. 35 is a view similar to Fig. 34, showing a further modification.

Referring to the drawings, and rst to sheet #l thereof, it will be noted that on this sheet I have illustrated an improved heat exchanger construction adapted for the effecting o-f heat transfer between two oppositely moving relatively wide and relatively shallow streams of fluid, and having improved means" for effecting a -substantially continuous remixing of the uids of the individual streams as they pass through the heat exchanger. This heat exchanger, generally designated l, includes a pair of headers 2 and 3, and a bundle or package 4 of plate elements 5 and 6, and outside plates I and 8. There are also provided partition elements 9, gaskets I0. and holding means Il and l2, the former holding the bundle of plates tightly together, and the latter holding the headers to the bundle of plates.

The plates 5 are plane and quite thin andare made of metal such as aluminum or stainless steel, land desirably are many times as long as they -are wide. Such metals `are chosen to 4reduce heat loss by conduction within the metal of the plates between the hot and cold ends of the exchangers. The plates 6, lwhich alternate with the plates 5, are of similar material and are plane except that they have pressed from their opposite surfaces protuberances l5, these protuberances in the construction shown Veach being in the form of a concavo-convex lor hollow rounded projection; and, by reason of the hollow nature of vthese projections, the plates may from one aspect -be regarded as dimpled, each dimple being .the recess Within a hollow projection. For some purposes, beads might simply be formed on the plates with-out hollow recesses, but this Vwould be somewhat less advantageous from the angle of simplicity of manufacture, for the plates can now simply be rolled between suitably constructed rollers and have lthe oppositely extending protuberances l5 formed on the same pass between the rolls. However, as above noted, my invention, except as expressly limited thereto, is no-t confined to hollowed out protuberances.

`The plate package 4 consists of a.considerable number of plates 5 alternating with plates 5, and this bundle of plates has at the sides thereof, the thicker, relatively rigid, outside plates 1 and 8. The protuberances I5 provide for relatively uniform spacing between the plates 5 and 6 and between the outermost plates 6 vand the Voutside plates] and 8. Theedges of the channels formed between the plates 5 and 6 and between the plates 6 and the outside plates 'I and 8 require sealing, and it is also desirable to seal, in the construction now being described, something more than one-half of each end o-f these passages, but to leave opening-s I6 and l1 diagonally opposite each other at the ends of the passages. For the purpose of providing the seals, the sealing elements or wires 9 are employed, and it will be noted, referring to Fig. 3, that these are in this case approximately L-shaped, and include longitudinally extending portions 9L and transversely extending portions 9E, the latter extending from one edge of the plates between which they are disposed to a point beyond the middle of the end-s of the plates, so that they may prevent the communication of certain header passages with certain of the flow passages between the plates. These flow passages may be hereinafter referred to as FI and F2, FI being the passage through which one of the fluids is to flow from one end of the exchanger to the other andr F2 being used to designate the alternate iiow passages employed for the conducting of the other of the two fluids in an opposite direction from the second end to the first. The headers 2 and 3 each contain two chambers extending for substantially their full depths. The chambers in the header 2 are numbered 2l and 22, while the chambers in the header 3 are numbered 23 and 24. Between each header and the bundle 4 there are gaskets I0, and each gasket has two openings in it, OI and O2. The gaskets are applied to the ends of the plate bundle 4 and the headers are secured against the gaskets by means of the holding means I2, shown as consisting of vertically extending bolts 26 having nuts 2l engageable directly or through suitable lock washers with flanges 28 on the headers, the bolts extending through the gaskets and also through flanges 29 formed on the outside plates 'l and 8. The chambers 2l, 22, 23 and 24 each have conduits connected to them, these being numbered respectively C2l, C22, C23, and C24, the conduits being secured in place as by studs 30 and nut-s 3| with the studs passing through flanges 32 secured to the conduits. Flanges 33 may be fixed tol the ends of the plate elements 5, 6, 'l and 8 and separators 9 to strengthen the construction. The separators are soldered or brazed in position, and may be individually brazed or soldered, or may be held in position by dipping the bundle in a suitable container containing molten solder or brazing material.

' The soldering or brazing of the various plate elements and separators together will provide a relatively strong fluid-tight construction, but additional means for increasing the ability of the heat exchanger to resist pressures in directions at right angles to the planes of the flow passages may be provided, as at Il above mentioned. For example, in Figs. l to 6 (excluding Fig. 4A) threaded tie rods 34 equipped with suitable nuts 35 at their opposite ends are shown extended through the edges 33 of the outside plates 'I and 8, further securely to hold the exchanger components together. Another arrangement for providing for a very secure and strong holding of the parts together consists in the tipping of each of the protuberances I5 with silver solder or the like before the plates are brought together in a completed stack, and then, by appropriately heating up the entire bundle of plates sufliciently to cause the silver solder toA effect connections as at 38 of the various protuberances to the plane plate surfaces which they contact, an exceedingly strong structure will be produced, for the number of ties in tension between the plates will be very large. Such an arrangement is illustrated in Fig. 4A, and with this form of arrangement it is unnecessary to use the tie rods 34 and nuts 35, though there is no objection to doing this, if it be desired.

The presentation of more extended description of this embodiment of the invention is scarcely necessary, but it may be pointed out that one fluid may enter through the conduit C22 into the chamber 22 and liow through all of the passages Fl to discharge at the opposite end of the heat exchanger into the chamber 23 of the header 3 and be delivered through the conduit C23, while simultaneously fluid delivered to the heat exchanger through the conduit C24 may flow from the chamber 24 into the passages F2 and out into the chamber 2| in the other header 2 and be led away by the conduit C2i. Because of the diagonal flow of the fluids, there will be a practically complete elimination of dead spots in the passages, and maximum eiciency of heat exchange will be secured. Because of the protuberances l5, even if there is a substantial difference in pressure in the different passages, there will be no serious tendency of the exchanger structure to collapse. Because also of the presence of these many protuberances arranged desirably for convenience in manufacture in longitudinal and transverse rows, the flowing streams of material will be subjected to recurrent turbulences which will effect reminglings of the warmer portions of the streams with the cooler portions thereof, and thus the maintenance of best conditions, i. e. maximum temperature differential, between the fluids at opposite sides of the plate elements, will be accomplished.

The three pass or course heat exchanger shown on sheet #2 of the drawings (in Figs. '7 to 16) does not require such extended description of its structure, because its essential differences from the rst form of the invention described inhere only in the modifications necessary to adapt the structure to the effecting of heat exchange among three streams of fluid. The following may he noted by way of preliminary. Since the invention is being illustrated in forms of construction particularly adapted for use in apparatus for the separation of air into its constituents, and since, in a preferred form of this type of apparatus where the fluids, when but two are involved, are air and the nitrogen constituent of the air, these fluids are desirably caused to flow alternately new in one and now in the other course of the heat exchanger intended for their confinement and guidance, the two passages, where but two are used, and the two principle passages, where there are more than two passages present, will be made of equal flow capacity. Where the oxygen, however, is also to be passed through the heat exchanger, it will require no such ow area as the nitrogen and the entering air require, as the oxygen is only about one-fifth, by volume, of the air. Accordingly, while the air and nitrogen conducting passages will be maintained substantially the same in number and in construction as in the first described embodiment of the invention, there will be interspersed among the air and nitrogen carrying passages a distinctly smaller number of oxygen conducting passages. And the headers willbe modified to provide three .sets of chambers, van

Y mouths -of the central passages t! or l2-and offthe openings'OS-fas well as one of the larger chamber mouths. There must, however, also be, further, -new type partition members t9, each .of which will have Aa portion 9E at both ends thereof. In other words, the members 49 are in the form of shallow Us with the open ends of pairs of these elements extending towards .each other .and spaced .apart as at 50 so as togpermit vthe chambers 4! and o2 and the openings O3 to communicate with the passages between plates whichvare separated from one another by the vnew forms of elements 49.

Referring .to Fig. 15, it will be observed, starting at the topof the figure as viewed in the drawings, that .there is a passage Fl, then a passage F2,

thenl if oxygen bethe other iluid to be passed through the heat exchanger, an oxygen conducting passage F3, and then, before `the next recul-rence of an oxygen conducting passage F3 there will be found .another passage Fi, another passage F2, a further passage FI, Vand a further passage. F2. Thereafter, following the next passage F3 there will be two other pairs of passages Fl and F2 before the next passage F3. The particular number of passages FIl and F2 for each passage F3 is not to be regarded as critical, as there might be even more passages Fi and F2- even as many as four or ve of each, for each passage F3.

This modication does not need further detailed description. Conduits I `and 52 held by studs and nuts 53 and '5d to the headers 2 and 3' serve for the conducting of oxygen relative to the chambers 4l and 2. The headers are held in Vposition relative to the other structure, and the outside plates and the individual plates are secured together and sealed, in a manner or manners similar to those described *with respect to the rst embodiment of the invention. It will be evident that through certain passages, air and nitrogen ilow in alternation in heat exchange relation to each other; that through certain other passages air and nitrogenV flow in heat exchange relation to the oxygen. The precise arrangement, however, of -the passages need not be as illustrated and,for example, there might bean air conducting passage at each side of each oxygen conducting passage. The turbulence eifected, the remixing of the fluids in the individual streams, the additional heat transfer area provided by the protuberances, the very efcient heat exchange accomplished by the thin streams and thin wall members, and the reinforcement'against fracture of the plates or collapse of the passage forming walls .are all present with this construction also. Desirably, valve means will be provided and arranged in association with the heat exchangers so far described, so as to cause the nitrogen always to flow in one direction and the air to always ilow in the other direction regardless of which passage series may be conducting nitrogen `andair, and desirably the oxygenwill always ow in onedirection-counterow to the air when the .construction of sheet #2 is employed.

While references have i been -made to nitrogen, air-and oxygen, it will be Iunderstoodthatthese have-beenfreferred to because of the .reference-to the special suitability of ther heat vexchangers illustrated and described to'airgseparation adjuncts, but my invention is in no sense-limitedto these elements or veven lto gases and/or-vapors.

VThe structure of sheet #3,v namelyfthat shown in Figs. v1'? to v22,'may next beaconside'red. The principal Vdifference of `this two-.pass'heat exchanger from the constructionrrst described-resides in themanner of and'thestructurefor effecting distribution of the iluidstobe'treatedin the `heat "exchanger through rthe passages ..pro-, vided 'between the'plates. .Itiwill bef'o'bserved'referring particularly to Figs. v19 and r*20, .thatthe plates .5",1which'are provided with..thefprotuber. ances l5, and the plane plates 15 .are each provided adjacentlitsropposite'ends@with pairs of circular vopt-:ningss and 6l, lit being Vnoted that the openings GE) are formed inthe plates 6 and the'openings 6| in the plates 15". These openings are inline with each other, and, accordingly, without additional structure all of 'the passages between the plates would bein communication with each other. Accordingly, I provide Yrings 63 associated withcertain of the plates as hereinafter described, 'these rings being-ofthe same internal diameter as the openings-6iland 6I and the same thickness axially as Vthe projection of the protuberances `I5 from the plates ii". Outside plates 7 and 9" are provided, the outside plates 8, except for dimension, being not diierent in any substantial way'fromthe outside plates 8. The outside plates l", however, are provided with thickened annular `portions 64 providing seats 65 to which conduits 66 may be held by suitably Athreaded means 61, the seats being traversed by openings S8 which'line up with the openings 60 and 6|.

In order to distinguish'the parts more readily during further explanation, the four conduits 66 may be identified .individually as 65', 5S, 85"', and 65", and the openings E8 may correspondingly be individually identified 'as6S 68, 68"', and 68".

Now it may be desired to cause fluid to enter through the opening 58 and-to pass through onehalf of the passages between the .plates and to leave the heat exchanger through the diagonally opposite opening 58". It will then bedesirable to have the other fluid to be treated in the exchanger enter through the opening 68" `and leave through the opening 6-8". It is, therefore. necessary to seal olf certain passages .between the plates from communication with lthe openings 63 and 68" and to seal oli certain other passages from the openings 623'" and 68". This sealing off is effected by the rings 63; Accordingly, referring now to Fig. 20, it -will be observed that there is no ring 63 between the outside plate l and the adjacent plate 2'2"', in coaxial relation with the opening '68', while there is a ring coaxial with the opening '63' between the above mentioned plate 6 and the Vadjacent'plane plate 5, and this arrangement of rings and plates continues to the outside plate 8" fof the heat exchanger with respect to the openings 4through the plates which are coaxial with the opening S8. Referring next to Fig. 19, it will be'observed that with respect to the openings coaxial with the opening 65", the rings G3 are arranged just the Vsame as they Aare with respect `to the opening 68', and, accordingly, assuming the direction of flow inward at B8 'and yout "at 682 it will be observed that flow takes place through the first, third, fifth, etc. passages between the plates from 68'V to 68. With respect to the flow in the other series of passages between the plates, it may be observed that with respect to the openings coaxial with the opening 68', there is a ring between the outside plate l and the adjacent plate 6, while there is no ring between this plate 6 and the plane plate 5" immediately next to the aforesaid dimpled plate 6". This arrangement of rings B3 continues to the outside plate 8" of the stack. With respect to the opening 68" at the opposite end of the exchanger, it will again be noted that there is a ring between the outside plate 1" and the adjacent one of the dimpled plates 6" and no ring between this plate 6" and the adjacent plane plate 5". This type of ring arrangement continues also to the outside plate 8". Accordingly, fluid entering through the opening 68" may leave after moving through the full length of the passages which communicate with the opening 68 out through the opening 68, owing in counterfiow relation to the fluid entering 68 and leaving at 68". The rings in this construction will be brazed or soldered to the plates at each side of them and because the headers are between the ends of the plates, the seals 'I0 may be caused to run all the way around the outside edges of the various plates, being brazed or soldered to the plates in any suitable manner as previously suggested. The wires or seals (or partition members) l may be round or square in cross section, or of any other desirable shape. tie bolt devices 12 may be arranged to clamp the heat exchanger elements firmly together, theses clamps being arranged adjacent the extreme end of the exchanger unit and also at various appropriate points along its length. They remove the necessity for reliance exclusively on brazing or soldering to hold the parts of the unit-s together. This construction needs no general description, because it is obvious that one fluid entering at one corner Will pass through one-half of the passages between plates and out at the diagonally opposite corner, While the other fluid will enter at the opposite side of the end of the heat exchanger at which the rst uid leaves and Will itself emerge from the diagonally opposite corner of the exchanger. The turbulence, the internal reinforcing, the effective heat transfer through thin plates, the strong and rugged construction, and other features of the earlier illustrative embodiments are obviously present in this construction also. As with respect to the first construction described, there may be in this and also in the last preceding form brazing or soldering of protuberances to adjacent plates, for greater strength and increased heat transfer.

Turning now to the modifications disclosed on sheet #4 of the drawings, in Figs. 23 to 35, the specific modification shown in Figs. 23, 24, 25, 26, 27, 28, 29 and 30 may be first noted. There is, practically speaking, but one difference between this modification and the modication shown in Figs. 17 to 22 inclusive. This difference resides in the making of the plates and the partition elements in the form of nesting pans. In other Words, each of the dimpled plates 6 is provided with a dimpled upright section 15 and a peripheral flange portion 16, the flange portions sloping outwardly in each case with respect to the upright section l5, and projecting laterally from the upright section 15 a greater distance than do the protuberances l5. The plate sections Cross bars Il and,

5" are also formed with planeupright sections l1 and outwardly flaring flange portions 18, so that they are in the form of shallow pans, and the flare of the flange portions 76 and 18 is such that when a pan section 5" is slipped into and placed with its plane portion in contact with the protuberances I5 on a section 6', there will be substantial contact between the flanges on the two sections as well as substantial contact between the protuberances and the upright section of the overlying pan section. In like manner, the opposite lateral projection of the protuberances l5 from the upright section of a pan or plate section 6"' is such that when these contact the plane surface of an upright section of a pan or plate section 5 into which the section 6"' is fitted, the outer walls of the rim or flange 'I6 will contact the inner wall of the rim or flange 18. Thus, simply by flowing solder into the joints between the rims or flanges of the various plate or pan sections, or by brazing these rims or flanges together, a very effective heat exchanger can be secured, it being necessary, however, still to use `rings Ih3 in connection with the openings which are provided to establish communication between the supply and discharge connections and the passages between the plates. All of the advantages of the modification of the invent-ion last described, plus the further advantage of a simple and very rugged and very easily and effectively sealed heat transfer unit, are present in this modification of Figs. 23 to 30.

It will be understood that by appropriately cutting away the end flanges on the plates-as by cutting completely away perhaps two-fifths at diagonally opposite corners on one series of pans and perhaps two-fifths at the other diagonally opposite corners on the other series of pans and using end headers as in the first embodiment describedythe large openings 60, 6I and the rings 63 can be omitted, and it will further be understood that additional strength can be attained by soldering the tips of the protuberances to adjacent plates as in Fig. 4A.

Many of the advantages of the invention can be obtained without employment of the dimpled platesand it is possible, for example, to use entirely plain plates having plane upright sections and peripheral flanges as in the modification last described, and to provide, instead of the dimpling, rows of helically wound metal ribbon arranged transverse to the direction of longitudinal flow of the fluids through the heat exchanger. These helically wound ribbons will extend, except where interruptions may be necessary because of the openings through the upright sections of the pan, tray, or plate sections, completely from side to side of these sections. If it be desired, in the interest of ease of winding the ribbons in helices, to increase the distance between the adjacent parallel surfaces of the adjacent plates, the angle of the pan rims may be changed in such manner as to cause contacts with the helices and between the rims to occur substantially simultaneously The helices may be initially bonded, as by brazing or soldering, to the opposite sides of a single plate, and if desired upon the assembly of the unit, brazing or soldering of the opposite sides of the helices to the plates which are brought into contact with them may be effected.

Referring briefly rst to Fig. 31, it will be noted that there are a plurality of helices, as of aluminum or stainless steel, or other suitable wire, shown at Sil, extending transversely to the right sections designated as 8 IP, and others have secured-brazed or solderedto their upright sectionslH the helically wound metallic ribbons' 89, these being bonded to the upright sections BIH as indicated at 85. If desired, by

dipping the unit or in any other appropriate manner, there may be an effective bonding of theihelices at their'sides contacted by the plain upright sectionsV 8IP, as shown at 86 in Fig. 85. With this construction, the flow through the passages formed between the partition forming portions lP and BlHof the pan sections Will be accompanied byyery effective turbulence with the result that there will be a continuous remixing oi each flowing fluid. rIhere willV also be a highly eiiicient heat exchange, because the helically Wound wires provide avery large area for the effecting of heat transmission, and by their bonding to the plates, insure the rapid transfer ofthe heat'which they may absorb to the adjacent plates.

Since'thev fluid distribution through this particular illustrative embodiment of the invention Will be the same as in the last two described, it needs no detailed noting at this point. It will be4 observed, however, that a very rugged structureV is produced because the convolutions of the helices being much closer together than the dimples, will provide the equivalents of struts ybetween the plates at closer intervals.

Ythat the A heatI transfer effecting areas will be much increased.

It will be understood that the end typeV of rifi-arjlfoldingillustrated with respect to the first speciesof the invention may be applied equally vvellrtov all other species shown as having a dif ferent' form of manifolding, it being necessary only to remove at appropriate points portions ofthe separators, rims or flanges and to provide and securein position the end type headers and gaskets.

In' allV the forms of the invention disclosed, Aexceedingly eiiective heat exchange will be Vaccomplished. In allrthe forms a rugged structure is secured and despite the minimization of wall thickness these heat exchangers can be used withfluids under quite different degrees ofA pressure. In all forms, though more so in some than in others, a readily assemblable and effectively scalable construction is provided. In

' all forins, thev feature of turbulence within the flowing Iiuids is present. Turbulence due to changes in'velocityas well as turbulence by the creation of eddies and impingernents on transverse surfaces will be observed to be present in variousv embodiments disclosed. On the whole, it will be observedthat each embodiment of the invention well meets the,criterion-of-A efciency set'forth earlier in thisV specification.

While there are in this application specifically described ve formsV and: certain modifications which the invention may assurneinY practice, it will be understoodthat these forms and modifications of the'same are shown for purposes' of illustration and`r that the invention may be further modied and embodied inl various other forms without departing fromitsspirit'or" thc scope of the appendedclaims.V

What I claim asin'e'w and" desire to secu-'re' by Letters Patent` is: Y A

1. A heat exchanger comprising a series of nested shallow pans ldefining narrow iow passages; and turbulence creating meanscooperatively associated-withsaid pans in saidflow pasi sagesV for repeatedly remixing the portions of the fluid flowing through'r said passages', said turbulence creating meansbeing in theform of helical coils arranged cross-wisein' said fio'w passages and secured to both sidesofl the bottoms of alternate pans'only, the pans between said alternate pans being in contact with but not secured to the coils.

2. In combination,- in a plate type `heat exchanger, a pluralityof heat conductingv plates each having a multiplicity o'f' closely packed .helical coilsv securedtoboth' sides of theplatear'i'd a rim flaring outward from said plate and extending abovethe tops' of said coils,.a plurality of other plates-each having a ri'ml or! side` wail ,Y flaring outwardY therefrom, said lastf-'Inenticned Number Name Date 641,992 Nussbaum- ;Jan, 23,1900 750,885' Nelson Feb. 2; 1904 1,409,967 Prat Mar.'21', 1922 1,559,1804 Prat Oct.27,.1925

1,805,652 Caracristi' May 19, 1931 2,217,567 Seligman et aL` Oct'. 8, 1940 2,281,752 Dalzell May 5,1942

2,439,208 Gloyer Apr.V 6i- 1948 FOREIGN PATENTS Number Country Date 808,844 France Nov. 24; 1936 96,981 `Sweden Oct. 3, 1939 

